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Table 3 Clinimetric properties of the DEMMI

From: The de Morton Mobility Index (DEMMI): An essential health index for an ageing world

Clinimetric property

Development study 17 items

Validation study 15 items

Reliability, MDC 90 (95%CI)

  

   Inter rater

9.5 (5.0 to 13.3), n = 21

8.90 (6.3 to 12.7), n = 35

MCID (95%CI)

  

   Criterion based method

7.8 (5.3 to 10.2)

9.43 (5.9 to 12.9)

   Distribution based method

8.0

10.5

Construct Validity (r, 95%CI)

  

Convergent

  

   HABAM

0.92 (0.88 to 0.95), p = 0.00

0.91 (0.87 to 0.94), p = 0.00

   Barthel Index

0.76 (0.65 to 0.84), p = 0.00

0.68 (0.56 to 0.77), p = 0.00

Discriminant

  

   MMSE

0.36 (0.16 to 0.53), p = 0.00

0.24 (0.05 to 0.41), p = 0.02

   APACHE 11

-0.11 (-0.32 to 0.11), p = 0.18

0.07 (-0.12 to 0.26), p = 0.49

   Charlson

-0.19 (-0.39 to 0.03), p = 0.11

-0.04 (-0.23 to 0.15), p = 0.68

Known Groups (DEMMI, 95%CI)

  

   discharge to rehabilitation

37.54 (33.99 to 45.10), n = 11

50.75 (42.39 to 59.11)n = 8

   discharge to home

59.61 (56.32 to 62.90), n = 62

Independent t test: p = 0.00

62.14 (57.80 to 66.49) n = 70

Independent t test: p = 0.03

Responsiveness to change #

  

Effect Size Index #

  

   DEMMI

0.37 (0.28 to 0.46)

0.39 (0.28 to 0.50)*

   HABAM

0.31 (0.20 to 0.43)

0.35 (0.23 to 0.47)

   Barthel Index

0.30 (0.17 to 0.44)

0.13 (0.01 to 0.25)*

GRI (patient) #

  

   DEMMI

1.23 (0.90 to 1.56)

0.92 (0.66 to 1.17)*

   HABAM

1.00 (0.46 to 1.55)

0.72 (0.49 to 0.94)

   Barthel Index

0.48 (0.01 to 0.95)

0.43 (0.21 to 0.65)*

GRI (therapist) #

  

   DEMMI

2.06 (1.60 to 2.51)

1.73 (1.37 to 2.09)*

   HABAM

2.62 (1.70 to 3.54)

1.17 (0.86 to 1.48)

   Barthel Index

1.58 (0.56 to 2.60)

0.65 (0.37 to 0.93)*

Floor effect

0%

<1%

Ceiling effect

<1%

3.8%

Time to administer, mean (sd)

13 mins 42 seconds (4.99 mins) for 42 mobility items

8 mins 47 seconds (3.89 minutes) for 17 mobility items

  1. GRI = Guyatt's Responsiveness Index, # Tryon's inferential confidence intervals
  2. * significant difference: evidenced by non overlapping inferential confidence intervals